1. Field of the Invention
The present invention relates generally to sheet metal, and in particular, to a method, apparatus, and article of manufacture for creating true manufacturing data and a true manufacturable lofted sheet metal shape.
2. Description of the Related Art
Many users design transitional (or lofted) sheet metal shapes for items such as air ducting, chutes, covers, etc., and design them using “smooth” transitions around the surface because designing that way is easy. However, when manufactured, many of these parts are not manufactured with these complex bends because of tooling costs. Instead, they “triangulate” the deformed area and create it using a series of regular bends and flat areas.
Modeling the true manufactured part is very hard to do, and creating the manufacturing pattern from a “smooth” model is a time intensive process. What is needed (and is lacking from the prior art) is the capability for a user to create a model “as manufactured”, while using the simplicity of creating design like they would with a smooth model. The problems of the prior art may be better understood with an explanation of prior art methods for developing triangulated shapes and bend lines.
FIG. 1 illustrates examples of developing a triangulated transitional shape in the prior art. As shown, the user must manually create the various triangulations and transitional shapes to enable a manufacturing pattern that can be used to produce an accurate model. For example, to create shape 102, triangulations are manually created as shown by images 104-108 with the true lengths mapped out. The resulting pattern is shown at 110. Similarly, to create shape 112, the transitional shapes 114-118 are used to create pattern 120. Such a creation process is time and processor intensive.
In the prior art, the problem with creating the transitional shapes and the flat pattern for manufacturing was solved in one of two ways:
A first method solved the problem by creating a series of cosmetic “bend lines” to approximate where the standard bends would be created. This suffered from three major problems:
(1) The bend lines could not be adjusted on a bend zone by bend zone basis, so the bend lines were not necessarily in an accurate location nor did they have the necessary flexibility to accurately use the flat pattern;
(2) The bend lines had no associated bend manufacturing information since the model was still smooth, the bend angle to bend the part at each bend line could not be calculated, so manual triangulation had to be done regardless; and
(3) Since the competition did not automatically generate an accurate starting and ending profile, users in certain competitive packages had to create a more complex profile just to get these cosmetic bend lines.
The second method of solving the problem was to manually calculate and build the “triangulated” model from scratch in the software. Such an approach was a time consuming, manual, and error prone process, and changing or editing the design was very difficult. FIG. 2 illustrates two figures used to manually create the sketch profile to create the “triangulated” shape of the prior art. A simple input profile 202 is used, followed by the manual calculation and building of the manual triangulation profile 204.